Remark 2.4 The continuity of the inclusion of the \(W^s_2(n_\theta ) \subset C(n_\theta )\)  for \(s>n/2\)  is established in [1]} (see also Remark REF  below). We obtain compactness by factorizing it through any inclusion \(W^s_2(n_\theta ) \subset W^{s^{\prime }}_2(n_\theta )\)  with \(s>s^{\prime }>n/2\) .

